Wednesday, 4 May 2016

Locating neighborhood diversity in the American metropolis

In
recent years, the growing racial and ethnic diversity of American suburbs
relative to their central cities has attracted significant attention in the
popular media.This is perhaps best
exemplified by writer Alan Ehrenhalt’s suggestion that a “demographic
inversion” characterizes many large American cities, in which old models of
central city diversity in contrast to suburban homogeneity no longer hold.

The
purpose of my article is to explore this shifting geography of metropolitan
diversity in US metropolitan areas, and suggest some methods of exploratory
data analysis and visualization to accomplish this.One such proposed method is a diversity gradient, which I define as a
smoothed curve fit through a scatterplot that displays neighborhood-level racial
and ethnic diversity scores against neighborhoods’ distances from their
respective urban cores.Diversity scores
are represented with a metric called the scaled
entropy index, in which a score of 1 represents perfect evenness between
non-Hispanic whites, non-Hispanic blacks, Asians, and Hispanics.An example diversity gradient from the
article for Dallas-Fort Worth, Texas is below.

The
visualization suggests greater homogeneity in urban neighborhoods around 5
miles from central Dallas and Fort Worth when compared with neighborhoods 15-20
miles from the downtowns, where the most diverse neighborhoods in the entire
metropolitan area tend to be located.

Additionally,
I explore geographic shifts in diversity over time through exploratory spatial data
analysis.I accomplish this through
identification of spatial “clusters” of high and low diversity neighborhoods in
the Chicago and Dallas-Fort Worth metropolitan areas, and compare the locations
of these clusters between 1990 and 2010.An example for Dallas-Fort Worth is found below.

As
the figures illustrate, high-diversity clusters (represented in red) within 10
miles of either core city hall in 1990 in some cases have given way to
low-diversity clustering by 2010, especially on the Dallas side of the
metropolitan area.High-diversity
clusters in 2010 tend to be located between 10 and 20 miles from the urban
cores, suggesting that neighborhoods of high racial and ethnic diversity are
increasingly more commonly found in the suburbs rather than closer-in
areas.

While
the article focuses on Chicago and Dallas-Fort Worth, I have developed an
interactive application at http://walkerke.shinyapps.io/neighborhood_diversity
that allows users to explore aspects of the analysis in the article for
themselves for many of the largest metropolitan areas in the United
States.Future research will expand
upon the exploratory spatial data analysis component of the article to identify
where within metropolitan areas neighborhoods tend to shift from high to
low-diversity clusters and vice versa, comparing these shifts among the US’s
largest metros.

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Urban Studies is the leading interdisciplinary journal for critical urban research and issues. Since it was first published in 1964 to provide an international forum for research into the fields of urban and regional studies, the journal has expanded to encompass the increasing range of disciplines and approaches that have been brought to bear on urban and regional issues